Thermostat case clamp



Sept. 1, 1959 F. SKAY 2,902,307

THERMOSTAT CASE CLAMP Filed Oct. 51, 1955 24 IN V EN TOR.

4 FRANK SKAY BY [III ,5

ATTO RN EYS United States Patent C) THERMOSTAT CASE CLAMP Frank Skay,Detroit, Mich., assignor to Holley Carburetor Company, Detroit, Mich., acorporation of Michigan Application October 31, 1955, Serial No. 543,729

6 Claims. (Cl. 292-256.6)

The present invention relates to an improved spring clamp unit to securetogether the housing parts of a thermostat case, such as is employed inan automatic choke of an internal combustion engine. It is a generalobject of the invention to materially simplify and expedite an assemblyof the thermostat by the use of a clamp in accordance with theinvention.

The conventional thermostat case for an automatic choke, as typicallyillustrated in the accompanying drawing, ordinarily has a casing part inthe form of a diecasting provided with suitable fittings to its hollowinterior and a further hollow casing member of molded material appliedthereto. In prior units, the two parts have been secured to one anotherby a plurality of screws threadedly engaging the die-cast part and aplurality of small spring clamp elements which engage the other casingpart, for example at a laterally projecting flange thereon, and aredrawn up by the screws to hold the casing members in rigidly clampedrelation, with a disklike sealing gasket compressed between the clampedparts.

A substantial factor in the cost of assembly of the thermostat case isthe time expended by a workman in assembling the individual springclamping elements to the case parts and holding same in proper positionuntil the clamping screws are taken up. Likewise the small individualclamping elements are frequently dropped and lost. Moreover, thenon-uniformity of pressure transmitted through these independent springclamps on the gasket and casing parts is undesirable, being usuallyexerted at only three widely spaced points about the case perimeter.Fracturing of a case part often occurs as a result.

It is therefore an object of the invention to provide an improved caseclamp construction in the form of a single one-piece spring clampingannulus or ring which consolidates the action of the plurality ofindividual clamp elements heretofore employed, and also multiplies theareas at which clamping pressure is applied, with a diminished angularspacing of the pressure points. This occasions greater uniformity ofdistribution of sealing 'force and eliminates the source of fracturingreferred to above. The cost of manufacture or assembly of the clampstructure is also substantially reduced.

More specifically it is an object of the invention to provide animproved casing clamp ring of special configuration, being of generallytriangular, but curved side, outline. The apices of the outline areaxially offset uniformly in respect to the general plane of the ring soas to provide 120 spaced spring components at these points; and theportions of the ring at the mildly rounded sides thereof are offsetslightly in the opposite direction, thus affording further intermediatespring components to double the number and halve the spacing of thespring areas or zones of the ring. Appropriate formations are providedat the ring apices to accommodate the usual case securing screws andhold the ring from movement in its plane. In assembly the ring istelescoped over a casing part, with its rounded sides abutting a flangeon this part and with its apex formations aligned with threaded holes inthe other part of the case. Screws threaded in the last named part atthese locations place the apex and intermediate spring portions of thering under 2,902,307 Patented Sept. 1, 1959 compression and flexure, andthe holding force of the screws is transmitted by them to clamp the caseparts and gasket rigidly.

The foregoing as well as other objects will be made more apparent asthis description proceeds especially when considered in connection withthe accompanying drawings, wherein Fig. 1 is a top plan view, partiallybroken away and in section, of an automatic choke thermostat case havingits parts clamped by a one-piece spring unit in accordance with theinvention;

Fig. 2 is a side elevational view of the assembly of Fig. 1;

Figs. 3 and 4 are, respectively, perspective and side elevational viewsof the improved one-piece clamp ring of the invention; and

Figs. 5 and 6 are, respectively, fragmentary sectional views in enlargedscale along lines 5-5 and 6-6 of Fig. 2.

The case 10 of an automatic choke thermostat as illustrated in Figs. 1,2, 5 and 6 of the drawings is of a known construction, comprising alower die-cast housing or casing part 11 having suitable externalfittings 12 opening to its hollow interior 13. The upper casing part 14is in the form of a circular cap provided with a radially outwardlyprojecting annular flange 15 about its open end, and which part 14 maybe fabricated integrally ol a non-metallic plastic composition or likemoldable material. A disk-like gasket 16 of appropriate fibrous sealingmaterial is compressed between flange 15 and an annular upwardly facingshoulder 17 of the part 11, this disk being in face engagement withmetal disk 18 applied across the internal opening of part 11.

A plurality of clamping screws 19 are threadedly engaged in individual,integral gasket centering bosses 20 projecting upwardly from shoulder 17at three equally spaced points about the perimeter of the latter. It hasbeen the custom in the past to employ an individual spring clamp elementof special shape at each of these bosses 20 to hold the casing part 14fixedly to the other part 11. This practice has the drawbacks referredto above.

In order to correct these disadvantages, and at the same time materiallyreduce the cost of assembly of the unit 10 as a whole, the inventionprovides a single, one-piece clamp ring 22 as shown in Figs. 3 and 4 ofthe drawings which ring is employed in lieu of the indivdual clampelements mentioned in the preceding paragraph. Ring 22 is, asillustrated best in Fig. l in its assembled posi' tion, in the outlineof an equilateral triangle having it: apices 23 connected by mildlyrounded side portions 24 The apex portions 23 are displaced slightly outof the general plane in which lie intermediate portions 25 of tht sides24 of the ring 22, the displacement being provider to form corner springareas, the displacement being uni form in all instances. Theseintermediate portions 25 of the length of the sides 24 are flat. Theradius of our vature of the ring at the intermediate portions 25 is on];slightly greater than the external dimension of casing par 14, so thatthe ring 22 may be easily and quickly slippec' over that part to bringits intermediate portions 25 it flush engagement with the top of theflange 15 of part 14 The ring 22 is provided at the inner edge of eachoi its apex spring areas 23 with a notch or bay 26, these notches beinglocated in angular spacing from out another, and so as to be inalignment with the threaded openings 27 of the three bosses 20 of thepart 11 to receive the clamping screws 19. The screw heads 28 wil thenbear on the material of the respective apices 23 out wardly of theirnotches 26. It is evident that the notches thus act as locks to preventangular shift of the ring 22 relative to the part 11.

The relationship of the features of the ring 22 is sucl'. that the heads28 of screws 19 will be spaced outwardly from the wall of casing part1.4 when the unit is assembled. There is no direct alignment of theheads 28, the apex material of ring 22 and the flange of part 14, sothat the apex 23 as compressed by the screw does not transmit directcompression to the flange, likely to fracture the latter. It is underspring force alone at all of its clamped zones. The assembly is effectedby positioning the gasket 16 on the shoulder 17 of part 11, dropping thepart 14 onto the gasket, telescoping the ring 22 over the part 14, withintermediate flat portions 22 abutting the flange 15, positioning thenotches 26 in axial alignment with the threaded openings 27, and byapplying and taking up the respective screws 19.

' This causes the spring apices 23 to be placed under substantialflexure and compression, and the intermediate oppositely oriented springportions 25 are correspondingly stressed. The holding pressure on flange15 is distributed uniformly over six points of contact, and the gasketis accordingly compressed with substantially greater uniformity than hasbeen possible with the previous clamp spring arrangement. The holdingforce of the uniformly distributed spring action will follow up andcontinue to seal the gasket 16 effectively, even after considerableshrinkage over long service. Actually, although it is desirable that theclamp ring 22 be fabricated of a good grade of spring steel, this is notan absolute necessity and a coldrolled steel, case hardened .O03".005deep, is satisfactory.

It will be observed that the flat, coplanar portions 25 of the sides 24are arcuate and concentric and together define a circular clamping zone.The corner portions 23 are engageable by the clamping means 19, andthese cor ner clamp engaging portions are located radially outwardlyfrom the clamping zone so that direct rigid clamping pressure may not beapplied in the clamping zone. In addition, the clamp engaging portionsare also displaced laterally from the plane occupied by the clampingportions of the ring.

The drawings and foregoing specifications constitute a description ofthe improved case clamp construction in such full, clear, concise andexact details as to enable any person skilled in the art to practice theinvention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. A casing structure comprising a body having a continuous flatcircular seat and a plurality of fastener receiver portions spacedangularly around and located radially outwardly beyond said seat, acover having an edge portion of continuous circular shape engaged onsaid seat and located radially inwardly from said fastener receiverportions, a continuous annular ring of resilient material having arcuateportions overlying the edge portions of said cover intermediate saidfastener receiver portions and having radially outwardly extendingfastener receiver portions shaped to overlie the fastener receiverportions of said body, and fasteners located outwardly beyond the edgeof said cover and extending through said fastener receiver portions andpressing the fastener receiver portions of said ring toward said body tothereby urge the edge portions of said cover between said fastenersagainst said body.

2. A casing structure comprising a body having a continuous flatcircular seat and a plurality of fastener receiver portions spacedangularly around and located radially outwardly beyond said seat, acover having an edge portion of continuous circular shape engaged onsaid seat and located radially inwardly from said fastener receiverportions, a continuous annular ring of resilient material having arcuateportions overlying the edge portions of said cover intermediate saidfastener receiver portions and having radially outwardly extendingfastener receiver portions shaped to overlie the fastener receiverportions of said body, and fasteners located outwardly beyond the edgeof 'said cover and extending through said fastener receiver portions andpressing the fastener receiver portions of said ring toward said body tothereby urge the edge portions of said cover between said fastenersagainst said body, said ring being formed from flat spring metal theplane of which is substantially parallel to the general plane in whichlie the portions of said ring intermediate the fastener receivingportions thereof.

3. A casing structure comprising a body having a continuous flatcircular seat and a plurality of fastener receiver portions spacedangularly around and located radially outwardly beyond said seat, acover having an edge portion of continuous circular shape engaged onsaid seat and located radially inwardly from said fastener receiverportions, a continuous annular ring of resilient material having arcuateportions overlying the edge portions of said cover intermediate saidfastener receiver portions and having radially outwardly extendingfastener receiver portions shaped to overlie the fastener receiverportions of said body, and fasteners located outwardly beyond the edgeof said cover and extending through said fastener receiver portions andpressing the fastener receiver portions of said ring toward said body tothereby urge the edge portions of said cover between said fastenersagainst said body, the fastener receiver portions of said ring extendingout of the general plane in which lie the portions of said ringintermediate the fastener receiver portions thereof when said ring isunstressed.

4. A casing structure comprising a body having a continuous flatcircular seat and a plurality of fastener receiver portions spacedangularly around and located radially outwardly beyond said seat, acover having an edge portion of continuous circular shape engaged onsaid seat and located radially inwardly from said fastener receiverportions, a continuous annular ring of resilient material having arcuateportions overlying the edge por tions of said cover intermediate saidfastener receiver portions and having radially outwardly extendingfastener receiver portions shaped to overlie the fastener receiverportions of said body, and fasteners located outwardly beyond the edgeof said cover and extending through said fastener receiver portions andpressing the fastener receiver portions of said ring toward said body tothereby urge the edge portions of said cover between said fastenersagainst said body, the fastener receiver portions of said ring havingradially inwardly open fastener receiving slots therein.

5. A one-piece generally annular clamping ring formed of flat springmetal adapted to exert resilient clamping pressure at a plurality ofcircumferentially spaced areas in an annular clamping zone, said ringhaving a plurality of circumferentially spaced fastener receivingportions all of which are located radially outwardly of said clampingzone, and clamping portions intermediate said fastener receivingportions, said clamping portions traversing said clamping zone betweeneach pair of adjacent fastener receiving portions, the clamping portionsof said ring being flat and occupying a single plane, and the fastenerreceiving portions thereof being laterally displaced from said plane inthe same direction each of said fastener receiving portions being shapedto receive a headed fastener located wholly radially outwardly from saidclamping zone.

6. A ring as defined in claim 5 in which said fastener receivingportions have radially inwardly open recesses to receive the fasteners.

References Cited in the file of this patent UNITED STATES PATENTS693,367 Brooke Feb. 18, 1902 2,318,868 Kimbell May 11, 1943 2,415,753Newell Feb. 11, 1947 2,441,104 Schubert May 4, 1948 2,695,726 ChatfieldNov. 30, 1954 FOREIGN PATENTS 413,862 France June 4, 1910

